trauma
Nineteen trials involving 5445 women reported on this outcome, 5353 women contributed data. The result of meta-analysis indicated that women in lubricant group had a lower incidence of perineal trauma when compared with those in standard care group (RR 0.84, 95%CI 0.76 to 0.93; I2=99%; low certainty due to serious risk of bias and serious inconsistency) (Table 1, Figure S3).
Subgroup analyses showed that there was significant subgroup effect between parity groups (P interaction=0.01) (Figure S4), but not between lubricants type groups (Pinteraction=0.15) (Figure S5) and between overall risk of bias groups (P interaction=0.40) (Figure S6). The heterogeneity of multiparous women groups and obstetric gel groups was significantly reduced after subgroup analysis (I2=0% and I2=62%, respectively), while significant heterogeneity remained within nulliparous women groups and liquid wax groups (I2=99% and I2=99%, respectively). Hence, this heterogeneity might partially result from studies of nulliparous women and liquid wax.
The result analyzed based on parity showed that both nulliparous women (RR 0.85, 95%CI 0.77 to 0.95; I2=99%) (Figure S4) and multiparous women (RR 0.72, 95%CI 0.66 to 0.78; I2=0%) (Figure S4) in lubricant group had statistically difference in the incidence of perineal trauma when compared with those in standard care group.
Incidence ofepisiotomy
Twelve trials involving 3285 women were included in this outcome, 3193 women contributed data. The result of meta-analysis indicated that women in lubricant group had no statistically difference in the incidence of episiotomy when compared with those in standard care group (RR 0.77, 95%CI 0.62 to 0.96; I2=84%; very low certainty due to serious risk of bias, serious inconsistency and serious imprecision) (Table 1, Figure S7).
Subgroup analyses based on lubricants type and overall risk of bias were not significant subgroup effect between subgroups (Pinteraction=0.95 and Pinteraction=0.33, respectively) (Figure S8, Figure S9). The heterogeneity of obstetric gel groups and high risk of bias groups was reduced after subgroup analysis (I2=58% and I2=54%, respectively), while significant heterogeneity remained within liquid wax groups and low high risk of bias groups (I2=94% and I2=88%, respectively). This heterogeneity might partially result from studies of liquid wax and low high risk of bias (Figure S8, Figure S9).
When analyzed based on parity, there was not significant in the incidence of episiotomy in lubricant group versus standard care group for nulliparous women (RR 0.80, 95%CI 0.63 to 1.01; I2=85%) (Figure S10). There was insufficient data to perform subgroup analysis for this outcome for multiparous women.